Unit 3.4 HEMATOCRIT (HCT) MEASUREMENT; RBC INDICES

Question 1

refers to the proportion of whole blood that consists of red blood cells, expressed as a percentage of the total blood volume.

Answer 1

Hematocrit (packed cell volume/PCV)

Question 2

provides the clinicians with an estimate of the bods red cell volume and thus, the bloods ogen-carrying capacity.

Answer 2

Hematocrit

Question 3

is useful in screening for, diagnosing, or monitoring a number of conditions and diseases that affect the proportion of blood (e.g. anemias).

Answer 3

Hematocrit determination

Question 4

Other uses of hematocrit:

Used in the calculation of (?)
In rough (?)
The buffy coat portion can be used in the preparation of (?)

Answer 4

Absolute indices/constants

Quality Control calculations

buffy coat smears

Question 5

Hematocrit Reference ranges:
Male:
Female:

Answer 5

0.42 - 0 .50 / 41.5 - 50.4%
0.36 - 0.45 / 35.9 - 44.6%

Question 6

Indirect Hct Calculated as:

Question 7

Direct (Manual/Spun Hct) Computed as:

Question 8

Microhematocrit tube
Length: _________

Answer 8

75 mm

Question 9

Microhematocrit tube
Bore: _________

Question 10

Microhematocrit tube
Blood column:

Answer 10

at least 5 cm

Question 11

Microhematocrit tube
Plug/Seal: ________

Question 12

Microhematocrit tube
Centrifugation (RCF): __________

Answer 12

10,000 -15,000 g for 5 mins

Question 13

Wintrobe Tube
Length: ___________

Answer 13

115 mm

Question 14

Wintrobe Tube
Graduations:
Left: __________________
Right: __________________

Question 15

Wintrobe Tube
Diameter: _____________

Answer 15

3mm

Question 16

Wintrobe Tube
Centrifugation (RCF): __________

Answer 16

3,000 rpm for 30 mins

Question 17

Technical Errors

Answer 17

Excess anticoagulant - leads to RBC shrinkage
Prolonged-standing of blood sample prior to test
Insufficient mixing of blood
Improper sealing of tube leads to escape of red cells
Inadequate centrifugation/allowing the tubes to stand too long after centrifugation
Reading errors (e.g. parallax error)

Question 18

Physiologic Errors

Trapped plasma increases the (?)
Values taken immediately after (?)
Dehydration leads to (?)
Stasis which leads to (?)

Answer 18

packed cell volume/height

acute blood loss

plasma loss

hemoconcentration

Question 19

To check the accuracy of the RBC, Hb, and Hct values generated by an automated analyzers or by manual methods.

Answer 19

RULE OF THREE:

Question 20

The rules of three applies only to RBCs that are normal in

Answer 20

size and hemoglobin content

Question 21

RULE OF THREE: BASIC FORMULA

Question 22

If values are WITHIN and the RBCs are normocytic, normochromic =

Answer 22

report results

Question 23

If values are NOT within & the RBCs are abnormal in shape & hemoglobin content =

Answer 23

report results

Question 24

If values are NOT within but the RBCs are normocytic, normochromic =

Answer 24

Do NOT report

Question 25

Used to define the size and hemoglobin content of the red blood cell.

Answer 25

RBC INDICES

Question 26

Used in classifying types of anemia

Answer 26

RBC INDICES

Question 27

refers to the average volume of the individual red cells in a given blood sample

Answer 27

MCV (Mean Corpuscular/Cell Volume)

Question 28

Used as an estimation of the average size of the RBC

Answer 28

MCV (Mean Corpuscular/Cell Volume)

Question 29

Not dependable when RBCs vary markedly in size

Answer 29

MCV (Mean Corpuscular/Cell Volume)

Question 30

MCV =

Question 31

MCV = Reference Value: = Cells are microcytic = Cells are macrocytic

Answer 31

80 - 100 fL < 80 fL > 100 fL

Question 32

MCHC =

Question 33

MCHC = Reference Value: = Cells are hypochromic = Cells are spherocytic

Answer 33

320 - 360 g/L or 32 - 36 % < 32% 36%

Question 34

MCH =

Question 35

MCH = Reference Value:

Answer 35

27 - 33 pg

Question 36

refers to average Hb concentration of red cells in a given volume of blood

Answer 36

MCHC (Mean Cell Hemoglobin Concentration)

Question 37

The average weight of Hb per RBC

Answer 37

MCH (Mean Cell Hemoglobin)

Question 38

Always correlate with the MCV & MCHC

Answer 38

MCH (Mean Cell Hemoglobin)

Question 39

Directly proportional to the size of the RBC & the concentration of Hgb. in the cell.

Answer 39

MCH (Mean Cell Hemoglobin)

Question 40

represents the ratio of the standard deviation to the MCV (width of the histogram)

Answer 40

RDW (Red Cell Distribution Width)

Question 41

Index of relative anisocytosis; May also indicate poikilocytosis

Answer 41

RDW (Red Cell Distribution Width)

Question 42

RDW (Red Cell Distribution Width) Reference Value: indicates variation in sizes

Answer 42

11.6 - 14.6 % > 14.6%

Question 43

Average amount of Hb in each RBC compared w/ the average amount in a normal RBC.

Answer 43

Color Index (C.I.)

Question 44

C.I. =

Question 45

C.I. = Reference Value:

Answer 45

0.9 1.1

Question 46

%Hb =

Question 47

% RBC =

Question 48

Average size of a red cell as compared with the average size of a normal red blood cell

Answer 48

Volume Index (V.I.)

Question 49

V.I. =

Question 50

V.I. = Reference value:

Answer 50

0.9 1.1

Question 51

% Hct =

Question 52

Denotes the average amount of Hb per unit volume of RBC in relation to normal.

Answer 52

Saturation Index (S.I.)

Question 53

S.I. =

Question 54

S.I. = Reference value:

Answer 54

0.80 - 1.20

Question 55

The average diameter of red blood cell in microns.

Answer 55

Mean Corpuscular Diameter (MCD)

Question 56

Price Jones Method (Direct micrometry)

Answer 56

Mean Corpuscular Diameter (MCD)

Question 57

Mean Corpuscular Diameter (MCD) Reference value =

Answer 57

6-9 microns

Question 58

Average volume of the biconcave disk

Answer 58

Mean Corpuscular Average Thickness (MCAT)

Question 59

MCAT =

Question 60

MCAT = Reference value:

Answer 60

1.7-3.5 microns

Question 61

• Micro Method • Macro Method

Answer 61

Direct (Manual/Spun Hct)

Question 62

Wintrobe method

Answer 62

Double oxalate

Question 63

Haden's method

Answer 63

1.1% Na Oxalate

Question 64

Van Allen

Answer 64

1.6% Na Oxalate

Question 65

Sanford Magath Method

Answer 65

1.3% Na Oxalate

Question 66

Bray's Method

Answer 66

Heparin

Question 67

Adams Micromethod

Answer 67

Heparin

Question 68

Wintrobe Tube Sample

Answer 68

Undiluted anticoagulated blood

Question 69

Westergren Method Sample Original – Modified –

Answer 69

whole anticoagulated blood w/ 3.8% Na Citrate (4:1) 2.0 mL EDTA blood combined w/ either 0.5 mL NSS or 0.5 mL 3.8% Na Citrate

Question 70

Microhematocrit tube Length

Answer 70

75 mm

Question 71

Wintrobe Tube Length

Answer 71

115 mm

Question 72

Westergren Tube Length

Answer 72

300 mm ± 0.5 mm

Question 73

Wintrobe Tube Internal bore:

Answer 73

3 mm

Question 74

Westergren Tube bore:

Answer 74

2.65 ± 0.15

Question 75

Westergren Tube Length of blood column:

Answer 75

200 mm

Question 76

Microhematocrit tube Diameter:

Answer 76

1mm/1.2mm

Question 77

Wintrobe Tube Diameter:

Answer 77

3mm

Question 78

Westergren External diameter:

Answer 78

5.5 mm ± 0.5 mm

Question 79

Microhematocrit tube RCF:

Answer 79

10,000 - 15,000 g for 5 mins

Question 80

Wintrobe Tube RCF:

Answer 80

3,000 rpm for 30 mins

Question 81

CLSI Specification of westergren tube:

Answer 81

thick-walled glass or hard plastic

Question 82

Disposable Westergren ESR System

Question 83

– has a safety plug (non-absorbent material) that provides automatic zeroing

Answer 83

Dispette

Question 84

Vol. of capillary tube:

Answer 84

0.05 mL (2/3 is filled w/ blood)

Question 85

Wintrobe Tube 2 Graduations: (right); (left)

Answer 85

Hct ESR/sedimentation rate scale

Question 86

Distance of tip to band

Answer 86

4-6mm

Question 87

Technical Errors

Answer 87

• Excess anticoagulant - leads to RBC shrinkage • Prolonged-standing of blood sample prior to test • Insufficient mixing of blood • Improper sealing of tube leads to escape of red cells • Inadequate centrifugation/allowing the tubes to stand too long after centrifugation (<5 mins = false inc) • Reading errors (e.g. parallax error – human error)

Question 88

- leads to RBC shrinkage

Answer 88

Excess anticoagulant

Question 89

(EDTA: inv)

Answer 89

6-8

Question 90

leads to escape of red cells

Answer 90

Improper sealing of tube

Question 91

Physiologic/Physical Errors

Answer 91

• Trapped plasma increases the packed cell volume/height – poikilocytes & anisocytes • Values taken immediately after acute blood loss • Dehydration leads to plasma loss • Stasis which leads to hemoconcentration

Question 92

REFERENCE RANGE Hematocrit

Answer 92

Male 0.42 - 0 .50 Female 0.36 - 0.45 Children 0.45 – 0.60

Question 93

REFERENCE RANGE Wintrobe

Answer 93

Male 0-9 mm/hr Female 0-20 mm/hr Children 0-13 mm/hr

Question 94

REFERENCE RANGE Westergren

Answer 94

Male <50 y/o 0 -15 mm/hr >50 y/o 0 -20 mm/hr Female <50 y/o 0 -20 mm/hr >50 y/o 0 -30 mm/hr Children 0 - 10 mm/hr

Question 95

↑Hematocrit

Answer 95

• Polycythemia vera • Hemoconcentration • Dehydration

Question 96

↓ Hematocrit

Answer 96

• Anemia • Hydremia of pregnancy • Hydration

Question 97

↑MCV

Answer 97

• megaloblastic anemia (immature blood cell) • hemolytic anemia with reticulocytes • liver disease • normal in newborns

Question 98

↓MCV

Answer 98

• iron deficiency anemia (Pb binds w/ carrier prot of iron) • thalassemia • sideroblastic anemia (inc red cell incl) • lead poisoning

Question 99

↑MCH

Answer 99

• macrocytic anemia

Question 100

↓MCH

Answer 100

• microcytic anemia